Systems and methods of biometric analysis with adaptive trigger

ABSTRACT

Exemplary embodiments are directed to biometric analysis systems including one or more illumination sources configured to provide dim illumination to a scene including an object and configured to provide flash illumination to the object in the scene. The biometric analysis systems include a rolling shutter camera configured to capture one or more images. The biometric analysis systems include an adaptive trigger module configured to analyze the scene to detect the object in the scene during dim illumination of the scene, determine a position in a frame of the rolling shutter camera that coincides with the detected object in the scene, and arrange a delay between a start of image writing by the rolling shutter camera and a trigger of the one or more illumination sources such that a stripe of the flash illumination coincides with the detected object in the scene.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of priority to U.S.Provisional Patent Application No. 62/316,347, filed Mar. 31, 2016,which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to systems and methods of biometricanalysis and, in particular, to biometric analysis systems including anadaptive trigger configured to align an object (e.g., a subject, abarcode, or the like) within a camera field-of-view to improveapplication of flash illumination to the desired area of the object forcapture and analysis.

BACKGROUND

Security is a concern in a variety of transactions involving privateinformation. As an example, iris recognition is a well-accepted andaccurate means of biometric identification used in government andcommercial systems around the world that enables secure transactions andan added layer of security beyond keys and/or passwords. Due to theincreased security provided by iris recognition systems, an increase inuse of such systems has occurred around the world.

Traditional cameras used in biometric identification are generallyexpensive. Video cameras that use complementarymetal-oxide-semiconductor (CMOS) or semiconductor charge-coupled device(CCD) image sensors typically use electronic shutters to determine thetime period over which the sensor measures light. A trigger signal opensthe shutter for a predetermined time during which each pixel within thesensor array collects (integrates) incoming light. At the end of theexposure, the signal collected (integrated) in each pixel during theexposure remains fixed and is then systematically read out, converted toa digital signal, and processed to become an image. Pixels are thencleared and readied for the next exposure to light.

There are different types of electronic shutters used in the industry.FIG. 1 is a diagram of a traditional global shutter camera schedule ofevents for signal collection, including the timeline for exposure ofeach row of an image sensor in the global shutter camera. Globalshutters simultaneously expose an entire array of pixels, e.g., N rowsby M columns, during signal collection. During a single exposure event(during t_(exp)), light is simultaneously collected in each pixel. Whenthe global shutter closes, the light signal within each pixel representsthe image during the period of the single exposure. All pixels integratesignal over exactly the same period of time. Global shutter camerasavoid flash timing issues incurred when using rolling shutter cameras.However, global shutter cameras are expensive options for biometricanalysis, thereby increasing the overall costs associated with biometricanalysis systems.

Rolling shutter cameras save cost and size in their sensor design. FIG.2 is a diagram of a traditional rolling shutter schedule of events forsignal collection, including the rolling shutter timeline. Rollingshutters expose an array of pixels differently from global shutters. Arolling shutter system exposes a first row of pixels for an exposuretime (t_(exp)) and then commences to read-out the exposed row of pixelsfor digitization. The read-out process occupies a unique onboardresource for a period referred to as a read-out time during which noother row can be read-out. To minimize the duration of the totalexposure including the read-out process, the rolling shutter exposes thesecond row of pixels during a time that is equal to but delayed from thefirst row by a read-out time. The second row is thereby exposed to lightand ready to be read-out at the moment that the read-out process for thefirst row is complete. The third row is exposed to light for a timeinterval equal in length to that of the first two rows but delayedrelative to the second row by a read-out time allowing for the requiredtime to read-out the second row. The process “rolls” down the pixelarray reading row-by-row in sequence taking a total time equal to theexposure time for a single row plus the read-out time interval, timesthe number of rows. The time interval during which a row is exposed andtherefore the events captured by that row are different for each row fora rolling shutter sensor. This is a key difference from a global shuttersensor, especially when using a short flash.

As shown in FIGS. 1 and 2, the light collection time period for each rowof a sensor with a global shutter is simultaneous while the time periodsof light collection for each row of a sensor equipped with a rollingshutter are not simultaneous. Rather, light collection time periods foreach row of a rolling shutter are offset from one another with a delaybetween rows equal to the row read-out time. The different exposuretechniques result in image shearing. For example, FIG. 3 shows an imagein which a moving fan blade was captured by an image sensor with aglobal shutter with no or little distortion as compared to the samemoving fan captured by an image sensor with a rolling shutter shown inFIG. 4. Image shearing is an inevitable consequence of the row-by-rowtime delays built into a rolling shutter sensor in which each row “sees”the scene over a slightly different and offset time interval.

The row-by-row delay in exposure of a rolling shutter also has an effecton coordinating an exposure with flash illumination. As discussedherein, a flash refers to a short, intense period of illumination of asubject during which the light applied by the flash dominates othersources of light on the scene (e.g., the area surrounding the subject).FIG. 5 shows the exposure of each row during t_(exp) with the shadedregion indicating the duration of time of the flash illuminationoccurring simultaneous during t_(exp). In a global shutter, the exposureof all the pixels in a sensor can be coordinated with the application ofthe flash illumination to the scene. For example, if the period of theflash pulse is 1 ms, the global shutter can open simultaneously with thestart of the pulse and close simultaneously with the end of the pulse 1ms later. The flash illuminates the pixels during and only during theirglobal exposure. Light forming the image is, by assumption, dominated bythe light applied to the scene by the flash. If, for example, sunlightis present in the scene, the irradiance on the object from the flash issignificantly brighter than that of the sunlight during the flash pulsewhen pixels are exposed by the global shutter.

Coordinating a flash pulse with a rolling shutter exposure is morecomplicated than with a global shutter. FIG. 6 shows the rolling shutterexposure during t_(exp) for each row extending diagonally across thediagram, and the time period for flash illumination illustrated as thevertical shaded region t_(p). After a flash delay, the flash pulseoccurs between the start pulse and end pulse points of the diagram.Because the exposure period for each row is delayed from the previousrow by a short read-out time interval, illumination of a full framerequires that a flash pulse provide illumination during a period whenall rows are integrating light. Failure to meet this condition creates asituation in which some rows of pixels integrate light from the flashpulse while some do not, and perhaps some rows integrate light from onlya portion of the flash pulse. In this case, the image is unevenlyilluminated. As shown in FIG. 6, some rows are finished integratingbefore the flash starts and other rows do not start integrating untilafter the flash ends. In addition, other rows integrate a partial flashand some integrate the full flash. Thus, a subset of lines on therolling shutter sensor receive adequate illumination, but outside ofthis set of lines, the other parts of the sensor remain largely dark.

One example of a short flash pulse can be considered with respect toFIG. 6, which, across the top horizontal line, four horizontal dashedlines, and bottom lines, respectively shows row numbers 0, 200, 450,600, 850, and 1000. The flash pulse can start as row 200 of 1000 rowsfinishes integrating the signal and begins to read-out, indicated by thetop dashed line. The flash pulse can end as row 850 of 1000 beginsintegrating the signal, indicated by the bottom dashed line. FIG. 6shows that rows 450 through 599 receive the full illumination of theflash pulse, as bracketed by the middle two dashed lines. However, rows200 to 449 and rows 600 to 849 only receive a portion of the flashillumination while rows outside of these ranges, e.g., rows 1 to 199 and850 to 1000, receive no flash illumination. Assuming insignificantambient light, the resulting image would show an illumination stripesurrounded by dim regions. The transition from bright to dim at the topand bottom of the stripe is due to rows that receive flash illuminationover a fraction of the total pulse time. FIG. 7 shown a portion of animage acquired using a rolling shutter camera with a delayed flash pulsein which the recorded irradiance is plotted to show dark regions beforeand after the flash, ramp-up and ramp-down regions of partialillumination, and a plateau region of complete flash illumination. Theplateau region of FIG. 7 is not flat because the flash itself was notuniform over the field-of-view. As another example, an image capturedusing a rolling shutter camera would include a horizontal stripe with avertical height proportional to the duration of the flash illumination.In cases with bright ambient illumination, the un-flashed portion of theimage would appear, but might be significantly dimmer if the flashillumination is brighter than the ambient illumination.

When an image of a particular object is desired with a rolling shuttercamera, a trigger signal can be initiated by the sensor controller tofire the flash at a preset time relative to the start of image writing.For example, the flash can fire when the first line is written and canremain on for 50 of 1000 lines. The resultant image would be flashilluminated for the top 5% of the image and would be dark elsewhere. Thesame flash can be delayed until the 500^(th) line of 1000 lines,resulting in an image with a stripe of illuminated content approximatelyhalfway down the frame. With such an arrangement, the photographer wouldneed to align the subject within the camera field-of-view such that thestripe of illumination detected by the sensor corresponds to theposition of the desired object.

Traditionally, one solution to the problem of flash illuminating animage using a rolling shutter has been to use an extended period ofillumination, e.g., a flash pulse that is started simultaneously withthe beginning of the exposure of the first row of pixels and is notfinished until the last row of pixels has been exposed. The extendedperiod of illumination is needed to expose the entire image since imagelines are written sequentially rather than all at once (as is the casewith a camera including a more expensive and physically larger globalshutter sensor). This technique necessitates a longer flash pulsecompared to the global shutter case, and would show up in FIG. 6 as ashaded region covering all of the rows with a duration equal to theframe time. This technique would also illuminate the full frame shown inFIG. 7. Additional requirements on the flash in terms of power output,heating and reliability are needed based on the longer pulse for thistechnique. A longer pulse might also challenge requirements foreye-safety. For these reasons, full frame pulses with rolling shuttersare considered impractical.

Thus, a need exists for improved biometric analysis systems including arolling shutter that are capable of illuminating and capturing thedesired area of an object for identification without an extended flash.These and other needs are addressed by the systems and methods ofbiometric analysis of the present disclosure.

SUMMARY

In accordance with embodiments of the present disclosure, an exemplarybiometric analysis system is provided that includes one or moreillumination sources configured to provide dim illumination to a sceneincluding an object, and further configured to provide flashillumination to the object in the scene. In some embodiments, the dimillumination can be provided by an illumination source external andseparate from the biometric analysis system, such as ambient light,sunlight, any other light source, or the like (e.g., one or more of theillumination sources can be ambient light). In some embodiments, thebiometric analysis system can include a single illumination source thatprovides the dim illumination, with the same illumination sourceproviding the flash illumination at the determined time period. In someembodiments, the biometric analysis system can include a firstillumination source that provides the dim illumination, and a second(separate) illumination source that provides the flash illumination. Insome embodiments, the first illumination source can continue to providethe dim illumination during the flash illumination from the secondillumination source. In some embodiments, the first illumination sourcecan be automatically actuated into a non-illuminating configurationduring the flash illumination provided by the second illuminationsource, and automatically actuated into an illuminating configurationafter the flash illumination is complete.

The biometric analysis system includes a rolling shutter cameraconfigured to capture one or more images. The rolling shutter cameragenerally includes a frame with a field-of-view. The term “image” asused herein can include still frame images, video, combinations thereof,or the like. The biometric analysis system includes an adaptive triggermodule configured to be executed by a controller or processing device.The adaptive trigger module, when executed, can be configured to analyzethe scene to detect the object in the scene during dim illumination ofthe scene. The adaptive trigger module, when executed, can be configuredto determine a position in the frame of the rolling shutter camera thatcoincides with the detected object in the scene. The adaptive triggermodule, when executed, can be configured to arrange a delay (a timedelay) between a start of image writing by the rolling shutter cameraand a trigger of the one or more illumination sources such that a stripeof the flash illumination coincides with the detected object in thescene.

In some embodiments, the adaptive trigger module, when executed, can beconfigured to track movement of the object within a field-of-view of therolling shutter camera. In such embodiments, the adaptive trigger modulecan be configured to modify the delay between the start of image writingby the rolling shutter camera and the trigger of the one or moreillumination sources based on detected movement of the object within thefield-of-view.

In some embodiments, the adaptive trigger module can be configured todetect a region of interest of the object and arranges the delay suchthat the stripe of flash illumination coincides with the detected regionof interest of the object. In one embodiment, the region of interest ofthe object can include one or both eyes of a person.

In some embodiments, the object can be a person. In such embodiments,the adaptive trigger module includes a face finder configured to detecta face (and/or features of the face) of the person. In some embodiments,the object can be a physical item. In such embodiments, the adaptivetrigger module can include an identifier finder configured to detect aunique identifier (e.g., a barcode, a quick response (QR) code,combinations thereof, or the like) associated with the physical item.

In some embodiments, the one or more illumination sources can beconfigured to provide the flash illumination as a synchronized pulse offlash illumination. The flash illumination provided by the one or moreillumination sources is brighter than the dim illumination provided bythe one or more illumination sources. In one embodiment, the one or moreillumination sources can be near infrared (NIR) illumination sources. Insome embodiments, the adaptive trigger module can be configured to sweepan illuminated stripe down the frame as the rolling shutter cameracaptures the one or more images, analyze an illuminated section of theone or more images to identify a region of interest in the illuminatedsection, and stop sweeping of the illuminated stripe when the region ofinterest is identified.

In accordance with embodiments of the present disclosure, an exemplarybiometric analysis system is provided that includes one or moreillumination sources configured to provide dim illumination to a sceneincluding a subject and configured to provide flash illumination to thesubject in the scene. The biometric analysis system includes a rollingshutter camera configured to capture one or more images. The biometricanalysis system includes an adaptive trigger module configured to beexecuted by a controller or processing device. The adaptive triggermodule, when executed, can be configured to analyze the scene to detecteyes of the subject in the scene during dim illumination of the scene.The adaptive trigger module, when executed, can be configured toidentify the eyes of the subject as a region of interest. The adaptivetrigger module, when executed, can be configured to determine a positionin a frame of the rolling shutter camera that coincides with theidentified region of interest. The adaptive trigger module, whenexecuted, can be configured to arrange a flash pulse delay between astart of image writing by the rolling shutter camera and a trigger ofthe one or more illumination sources such that a stripe of the flashillumination coincides with the identified region of interest. In someembodiments, rather than or in addition to using dim illumination, theadaptive trigger module can be executed to search and find the region ofinterest by systematically sweeping an illuminated stripe down thefield-of-view and stopped when a region of interest is detected. Thus,rather than using a single frame (as in dim illumination), theilluminated stripe can be a fraction in width of the full frame and isadvanced across the field-of-view, thereby using multiple frames todetect the region of interest. The region of interest can be tracked bythe adaptive trigger module after being detected.

The flash pulse delay can ensure that the illuminated region of interestis substantially maintained in a center of the frame of the rollingshutter camera. The biometric analysis system can include a feedbackmodule configured to be executed by the controller or processing device.The feedback module, when executed, can be configured to analyze acaptured image of the region of interest and determine if the region ofinterest is illuminated by the stripe of the flash illumination. Theadaptive trigger module, when executed, can be configured to adjust theflash pulse delay based on the determination of the feedback module toensure that the region of interest is illuminated by the stripe of theflash illumination.

In accordance with embodiments of the present disclosure, an exemplarymethod of biometric analysis is provided. The method includesilluminating a scene and an object in the scene with dim illuminationfrom one or more illumination sources. The method includes analyzing thescene with an adaptive trigger module to detect the object in sceneduring dim illumination. The method includes determining a position in aframe of a rolling shutter camera that coincides with the detectedobject in the scene. The method includes arranging a delay between astart of image writing by the rolling shutter camera and a trigger ofthe one or more illumination sources such that a stripe of flashillumination provided by the one or more illumination sources coincideswith the detected object in the scene.

In some embodiments, the method can include tracking movement of theobject within a field-of-view of the rolling shutter camera with theadaptive trigger module. In such embodiments, the method can includemodifying the delay between the start of image writing by the rollingshutter camera and the trigger of the one or more illumination sourceswith the adaptive trigger module based on detected movement of theobject within the field-of-view.

In accordance with embodiments of the present disclosure, an exemplarynon-transitory computer-readable medium storing instructions forbiometric analysis is provided. Execution of the instructions by aprocessing device (or controller) causes the processing device toilluminate a scene and an object in the scene with dim illumination fromone or more illumination sources. Execution of the instructions by aprocessing device causes the processing device to analyze the scene withan adaptive trigger module to detect the object in scene during dimillumination. Execution of the instructions by a processing devicecauses the processing device to determine a position in a frame of arolling shutter camera that coincides with the detected object in thescene. Execution of the instructions by a processing device causes theprocessing device to arrange a delay between a start of image writing bythe rolling shutter camera and a trigger of the one or more illuminationsources such that a stripe of flash illumination provided by the one ormore illumination sources coincides with the detected object in thescene.

Other objects and features will become apparent from the followingdetailed description considered in conjunction with the accompanyingdrawings. It is to be understood, however, that the drawings aredesigned as an illustration only and not as a definition of the limitsof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

To assist those of skill in the art in making and using the disclosedsystems and methods of biometric analysis, reference is made to theaccompanying figures, wherein:

FIG. 1 (prior art) is a diagram of a traditional global shutter cameraschedule of events showing simultaneous exposure of each row betweenstart and end of exposure followed by simultaneous read-out.

FIG. 2 (prior art) is a diagram of a traditional rolling shutter cameraschedule of events showing start of frame, cascading exposure of pixelrows, and rolling read-out, with delay between rows being equal toread-out time.

FIG. 3 (prior art) is an image of a moving fan illustrating minimaldistortion as captured by a traditional global shutter camera.

FIG. 4 (prior art) is an image of a moving fan illustrating shearingdistortion effects caused by cascading row delays as captured by atraditional rolling shutter camera.

FIG. 5 (prior art) is a diagram of a traditional global shutter scheduleof events showing simultaneous exposure of each row between start andend of exposure followed by simultaneous read-out, with a flash firingduring the same time interval as that in which the rows are exposed(t_(exp)).

FIG. 6 (prior art) is a diagram of a traditional rolling shutterschedule of events showing start of frame, cascading exposure of pixelrows, and rolling read-out, with a flash firing after the beginning ofthe frame, illuminating some but not all rows, and some rows partiallybut others completely, resulting in a ramp-up, plateau and ramp-downperiods of flash illumination.

FIG. 7 (prior art) is a diagram of a vertical strip of an image(re-oriented horizontally to align with the time axis) showing dark,ramp-up, plateau, ramp-down, and another dark region due to timing offlash in a traditional rolling shutter frame.

FIG. 8 is a schematic block diagram of an exemplary biometric analysissystem in accordance with the present disclosure.

FIG. 9 is a representation of an image captured by a rolling shuttercamera of the exemplary biometric analysis system including a stripe offlash illumination across a region of interest.

FIG. 10 is a diagrammatic view of an exemplary biometric analysis systemin accordance with the present disclosure.

FIG. 11 is a diagrammatic view of a frame action of a rolling shuttercamera of an exemplary biometric analysis system in accordance with thepresent disclosure.

FIG. 12 is a flowchart illustrating an exemplary process of implementingan exemplary biometric analysis system in accordance with the presentdisclosure.

FIG. 13 is a flowchart illustrating an exemplary process of implementingan exemplary biometric analysis system in accordance with the presentdisclosure.

FIG. 14 is a block diagram of an exemplary computing device forimplementing an exemplary biometric analysis system in accordance withthe present disclosure.

FIG. 15 is a block diagram of an exemplary biometric analysis systemenvironment in accordance with the present disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

In accordance with embodiments of the present disclosure, exemplarybiometric analysis systems are described herein for a rolling shuttercamera that include an adaptive trigger for ensuring that the stripe oflight from the flash illumination illuminates a region of interest of anobject, such as the eyes of a person, during image writing. Thebiometric analysis systems generally include one or more illuminationsources that initially provide dim illumination to a scene to detect theobject and identify the region of interest of the object. Based on theidentified region of interest, a delay between the start of imagewriting by the rolling shutter camera and the trigger of theillumination source is arranged or coordinated to ensure that the stripeof the flash illumination coincides with the region of interest of theobject.

Cameras that include rolling shutter image sensors are typically cheaperthan those with global shutter image sensors. The exemplary biometricanalysis systems use flash illumination in combination with inexpensiverolling shutter cameras of the type found in low-cost cameras andsmartphones. The biometric analysis systems address a rollingshutter-specific problem that occurs when the brightness of the ambientlight in the scene may need an exposure time less than the full frametime to avoid saturation, and the exposure time is sufficiently shortthat the first rows of the image are finished integrating light andreading out before the last lines of the image have begun integration.In cases of short exposure times, a single, short flash pulse will notilluminate an entire frame, leaving portions of the frame relativelydark. Long exposure times can result in motion blur.

The exemplary biometric analysis systems balance the followingparameters to ensure the captured image quality is sufficient foridentification, and further ensuring that the region of interest isadequately illuminated by the flash: sensor frame rate, sensor exposuretime, flash pulse intensity, flash pulse duration, flash pulserepetition, processed frame rate, and flash pulse offset. Increasing thesensor frame rate over the available ranges increases the speed that thereset and read lines move over the image. For a given sensor exposuretime, increasing the frame rate effectively increases the number ofexposed lines during that period. For example, with the exposure timeremaining the same, the execution time of the internal clock of thecamera can be increased to operate the camera at a faster rate, therebycapturing a greater number of lines during the exposure time. Thedrawbacks of increased sensor frame rates are additional data transfersand additional heating due to higher clock speed. Lower frame rates maybe desirable for dark indoor lighting conditions and higher frame ratesmay be desirable for outdoor bright lighting conditions.

Increasing the sensor exposure time increases the distance between thereset and read times. This effectively increases the number of exposedlines during that period, allowing a short flash pulse to cover morelines. The drawback of increasing this period is that additional ambientlight is accumulated over the entire period. During outdoor operation,it may be beneficial to keep the exposure time as short as possible, butallowing enough lines to be covered by the flash. Keeping the exposuretime shorter is also important to avoid introducing motion blur whichcan degrade recognition performance.

The flash pulse needs to be bright enough to overpower direct sunlightfor effective outdoor operation. The flash pulse is limited by availablesystem power and eye safety limits. In general, eye safety can beroughly proportional to the total amount of energy absorbed by the eyeover a period of time (e.g., t^(−0.75)). Reducing the intensity, pulseduration, and pulse repetition all move the system into a saferstanding. Longer flash pulses allow more lines to be exposed in arolling shutter. However, longer pulses can lead to increased eye safetyconcerns forcing the system to use less intense pulses when longerdurations are used.

Several short flash pulses may be used back-to-back to illuminateadditional lines with minimal overlap between exposed lines. Thistechnique can reduce the total eye exposure and power requirements whileexpanding the total number of lines that can be properly illuminated.Pulse rate, duration, and intensity can all impact the system powerrequirements. Increasing any of these parameters generally increases thedemand for power.

In some embodiments, since eye safety depends on the total exposure overa period of time, one method to reduce the total exposure can be toselectively process frames. While images can be captured at 60 framesper second (fps), only one in four can be illuminated with the flash,which would reduce the exposure to an equivalent of 15 fps with theadvantages of capturing at 60 fps. Such technique allows for improvedline read speeds, bringing the rolling shutter camera closer to theglobal shutter camera timing.

In some embodiments, the systems can include a continuous feedback loopto a user who is attempting to align their eye with a small box on thescreen (e.g., in situations involving a smaller screen, such as asmartphone). The feedback loop allows the system to predetermine whichlines should be exposed. A low level of continuous, dim illumination canbe provided to ensure the user has a reasonable image to complete thistask. Depending on the available processing power and flash offsetcontrols, the continuously illuminated frames can be processed to detectspecular reflections, and further used to change the flash offset ordelay. Such operation allows the user additional margin when attemptingto place their eye in the box while keeping the exposure levels to aminimum.

The biometric analysis systems adjust the portion of the frame that isilluminated such that the important portion of the image (e.g., a regionof interest) is well-lit and the unimportant portions of the images areleft dim. The biometric analysis systems can be used in imaging in thenear infrared (NIR) spectrum using a short, intense, eye-safe NIR flashwith an NIR filter to freeze motion and emphasize the flash relative toambient light (including bright sun). The biometric analysis systemsincluding the NIR flash with a rolling shutter camera can be used in,e.g., iris biometrics, or the like, in which cost reduction realized byusing a rolling shutter instead of a global shutter is a primary driverin component selection.

The biometric analysis systems include an adaptive step in which dimillumination allows a vision system (e.g., a sensor in a rolling shuttercamera including a processor) to detect the position of the desiredobject in the field-of-view of the camera. In some embodiments, the dimillumination remains on for the entire process of capturing an image,and reveals an under-illuminated frame. Dim illumination, althoughdimmer than illumination by the flash, is bright enough to perform anautomated scene analysis, e.g., face finding, object identification, orthe like, that can output a recommendation of a position in the framethat would benefit from flash illumination. For example, if a faceappeared between 20% and 40% of the frame height measured from thebottom, a controller or processor can arrange a delay between the startof image writing and the flash trigger such that a stripe ofillumination coincides with the desired object. If the object moves inthe field-of-view, biometric analysis systems can function dynamicallyto track movement of the object and change the delay accordingly. Insome embodiments, rather than or in addition to using dim illumination,the adaptive trigger module can be executed to search and find theregion of interest by systematically sweeping an illuminated stripe downthe field-of-view and stopped when a region of interest is detected.Thus, rather than using a single frame (as in dim illumination), theilluminated stripe can be a fraction in width of the full frame and isadvanced across the field-of-view, thereby using multiple frames todetect the region of interest. The region of interest can be tracked bythe adaptive trigger module after being detected. Such arrangements tolocate and track the object and indicate to the adaptive trigger modulechanges in the position of the object permits moving objects to beaccurately imaged by the biometric analysis systems.

The biometric analysis systems disclosed herein can be used for rollingshutter photography (e.g., NIR photography) of objects while outdoors orindoors. The biometric analysis systems can acquire NIR images withcontrolled illumination in full sun or in dim ambient lighting. An imageof a desired object that fills less than a full frame, e.g., a person'sface with the entire person in the field-of-view, can be captured by thebiometric analysis systems. Due to the low cost, small size andavailability of rolling shutter sensors, incorporation of the biometricanalysis systems into cost-sensitive or size-sensitive platforms canbenefit cost-sensitive or size-sensitive users. As one example, thebiometric analysis systems can be used in cargo identification in whichinfrared dye for markings signify authenticity. As another example, abox marked with writing can be imaged with a small and inexpensivehandheld infrared camera that would look for the marking surrounding anNIR watermark.

The flash trigger can be adjusted to fire in order to illuminate themarkings, leaving the rest of the field-of-view above and below the markof interest in the dark. Handheld devices, including smartphones,barcode readers, and other mass produced electronic devices, canincorporate the biometric analysis systems at a small and low cost.Traditionally, a rolling shutter camera would reduce the cost for suchsystems, but would require an extended flash to illuminate an entirescene to guarantee capturing the subject of interest. The exemplarybiometric analysis systems include a rolling shutter camera with anadaptive image content-based trigger that issues a shorter flash of anear infrared light that allows for use of smaller batteries, providesfor a longer battery life, provides for improved eye safety, and allowsfor longer illumination source lifetimes.

The biometric analysis systems disclosed herein can provide flashillumination for illuminating an object sufficiently to outshine thesun, and in some embodiments can use strobing flash illumination as isdisclosed in, e.g., U.S. Pat. Nos. 7,542,628; 7,627,147; 7,657,127;9,131,141; U.S. Patent Application Publication No. 2015/0098630; U.S.Patent Application Publication No. 2016/0014121; U.S. Patent ApplicationPublication No. 2016/0012218; and U.S. Patent Application PublicationNo. 2016/0012292, which are incorporated by reference herein.

The exemplary biometric analysis systems use a rolling shutter cameraand a flash illumination that is triggered adaptively to illuminate theregion of interest of the scene or object. The adaptive trigger can beconfigured to follow or track the subject, and adjusts the flash timingto maintain the stripe of flash illumination on the subject of interest.In one embodiment, a face finder can be used as an image analytic totrigger the flash. In one embodiment, a unique identifier, such as a barcode or QR code, can be detected and illuminated by the stripe of flashillumination. In either case, the biometric analysis system can locatethe object in a relatively dimly lit scene, and then initiates therepetitive flash that illuminates the object. Flash timing can beadjusted to maintain the object in the illuminated region of thefield-of-view of the rolling shutter camera.

With respect to the delayed flash, an assumption can be made that thestart of integration of the first row of a rolling shutter sensorcoincides with time t=0. A further assumption can be made that a flashpulse is started at some time later, e.g., delayed by a time Δt. Rowsthat are read-out (e.g., integrate light) before At miss any light fromthe flash. Rows that are in the process of integrating light when theflash starts—some nearly finished, some just starting—receive fractionsof the flash and form the ramp-up region of partial illumination. Pixelsin rows that start integrating at or after the start of the flash andthat finish integrating light by the end of the flash are illuminated bythe full flash. By adjusting the delay time At, the rows of full flashillumination can be adjusted from the top of the image frame to thebottom to focus on a region of interest located within the frame.

In particular, the biometric analysis systems can be used to detect theregion of interest within the frame of the rolling shutter camera, andintentionally delay the flash illumination in a coordinated manner toensure that the region of interest is illuminated by the flash duringexposure and read-out of the corresponding rows. Proper adjustment ofthe delay time can cause the stripe of flash illumination due to theshort flash pulse to brighten the region of interest. In someembodiments, the stripe can scan or search the image in successiveframes of a photo or video stream. Such technique can be performed bysystematically sweeping an illuminated stripe down the field-of-view andstopping when a region of interest is detected. Thus, rather than usinga single frame (as in dim illumination), the illuminated stripe can be afraction in width of the full frame and is advanced across thefield-of-view, thereby using multiple frames to detect the region ofinterest. The region of interest can be tracked by the adaptive triggermodule after being detected.

In some embodiments, a pre-flash (e.g., a single long, low intensityflash that illuminates the full frame and that is both eye-safe andwithin the operating range of the illumination hardware) can provide asingle, dim image of the scene. Automated image analysis of the fullscene that can tolerate the low light can detect and output a region ofinterest that is the width of the image and the height of the flashillumination stripe. With the region of interest defined, an automateddelay signal can set the illumination stripe to the optimal position toilluminate the region of interest in succeeding frames of a photo orvideo stream using the full flash brightness over the narrowed region ofinterest. If the desired feature of the object begins to move out of theillumination stripe (as determined by video analysis performed at theframe rate), the delay can adapt using negative feedback to maintain theposition of the desired feature centered within the well-lit region ofthe image.

In some embodiments, the biometric analysis systems can be used tocapture NIR images of an object that is bathed in sunlight. While afraction of the solar spectrum covers the NIR wavelengths, it can beassumed that filtered solar NIR irradiance (e.g., from 800 nm to 900 nm)is insufficient to illuminate a video frame that is adequately short induration to suppress motion blur. It can be further assumed that using along flash that covers the entire rolling shutter frame period isimpractical, even with a short exposure time, due to hardwarelimitations or eye safety concerns. A short NIR flash pulse that canonly illuminate a portion of the frame with an adaptive delay time toensure that the region of interest is illuminated can therefore be used.

The biometric analysis systems initially detect and identify a region ofinterest of an object, such as the eyes of a subject. Eye finding can beaccomplished using a number of different processes, such as full frameNIR illumination with a relatively dim, eye-safe (and hardware-safe)long NIR flash pulse; partial frame illumination due to a short, intensepulse that is automatically swept frame-by-frame over the fullfield-of-view until the eyes appear in the search; and/or imageacquisition by a color (or other spectrum) auxiliary camera thatproduces a full frame image allowing eye-finding or face-finding, andthen translation from the auxiliary camera frame position to a NIRcamera position.

After the eyes are detected and their position located in the NIR cameraframe, the biometric analysis systems automatically set the flash pulsedelay to illuminate a stripe across the frame including the eyes (e.g.,the region of interest). The delay that sets the vertical position ofthe illumination stripe can be automatically adjusted to maintain theeyes in substantially the center of the frame. While the portions of theframe outside of the illumination stripe remain unusably dark, theimportant information about the eyes remains well lit.

The competing solar illumination may dimly illuminate the rest of theframe. This is not an issue as long as the flash illumination striperemains resolved and does not saturate due to the sum of the in-bandsolar irradiance and the applied NIR light. If the illumination stripenears the saturation level, the intensity of the applied flash can bethrottled back. It is preferable to decrease the NIR illuminationirradiance on the object rather than reducing the exposure or pulseduration, since the later strategies reduce the portions of the imagethat are illuminated.

Any spectrum of light can be used as long as the camera uses a rollingshutter with an in-band flash illuminator. For example, visible light,NIR, short-wave infrared (SWIR), long-wave infrared (LWIR), ultraviolet(UV), or multi-spectral cameras with rolling shutters that use flashillumination. Any process of finding the region of interest can be usedas long as the process returns a coordinate to the biometric analysissystem that indicates the time delay between the start of frame and thestart of the flash. For example, use of an eye finder that seeks cornealreflections of the flash could be useful if the region of interestcontains one or two eyes of the subject. As a further example, a colorface camera could be useful to find the eyes of a subject in irisrecognition; but if nose-recognition were used, the region of interestwould contain the subject's nose. If the same camera were used to findthe region of interest and to acquire the information from the region ofinterest, a different illumination protocol could be used for eachfunction. For example, a long, relatively dim pulse could illuminate theentire frame, followed by a short, bright pulse to illuminate the regionof interest with better fidelity (e.g., improved signal-to-noise ratio).Any process that provides the information needed to set the delay timewould also be useful.

In some embodiments, feedback can be used to maintain the region ofinterest in the illumination stripe. For example, negative feedback canbe used to correct the position of the region of interest within theillumination stripe. If the object of interest begins to move or slip tothe top or bottom of the region of interest illuminated by the flash,feedback can be used to correct the delay time. For example, if thestripe illuminating the region of interest needs to move up in the frameto follow the object of interest, the delay would need to be correctedin one direction. If the object of interest moves down in the frame, thesign of the delay correction would need to be in the opposite direction.If the delay reaches the minimum or maximum value or, in other words,the object of interest begins to leave the camera field-of-view, thecontroller or processing device automatically reorients the camera tomaintain the object in the field-of-view. In some embodiments, afeedback signal (e.g., an audio alarm, a visual alarm, combinationsthereof, or the like) can provide feedback to an operator regarding theobject leaving the field-of-view.

The width of the flash illumination stripe relative to the frame heightcan be set by practical considerations. For example, rolling shuttercameras with very short read-out times generally have wider flashillumination stripes, all other things being equal. The longest flashpulse can be dictated by practical issues, including available power tothe illumination source, operating conditions in power, and temperatureof the illumination source. For example, it is known that flashing anillumination source too often can damage it, and reduces the safety ofhuman eyes in and around the illumination source. A flash illuminationstripe that is narrow relative to the frame height generally should bemore accurately timed than a flash illumination stripe that is wider andthat can tolerate more motion of the object of interest within the flashillumination stripe.

With reference to FIG. 8, a schematic block diagram of an exemplarybiometric analysis system 100 (hereinafter “system 100”) is provided.The system 100 is configured to detect and identify a region of interestof an object, such as the eyes of a person, and generates a time delayof the flash illumination such that the flash coincides with the regionof interest. A rolling shutter camera can therefore be used forcapturing one or more images for biometric analysis with the delayedflash illumination ensuring that the region of interest will be properlyilluminated in the captured images. The system 100 is configured totrack the region of interest within the frame or field-of-view of therolling shutter camera, and adjusts the time delay of the flash pulseappropriately based on movement of the region of interest in and out ofthe frame.

The system 100 generally includes one or more illumination sources 102.The illumination sources 102 are configured to initially provide dimillumination 104 to a scene including an object to detect and identifythe object (or the region of interest of the object). In someembodiments, the dim illumination 104 can be separate from the system100 and can be provided by, e.g., ambient light, any other illuminationsource, sunlight, combinations thereof, or the like. The illuminationsources 102 are further configured to provide flash illumination 106(e.g., a pulse of flash illumination) to illuminate the region ofinterest during exposure of the rows corresponding to the region ofinterest, thereby ensuring that the region of interest will beilluminated in the captured image. In some embodiments, a singleillumination source 102 can provide both the dim illumination 104 andthe flash illumination 106. In some embodiments, separate illuminationsources 102 can provide the dim illumination 104 and the flashillumination 106. In one embodiment, the illumination sources 102 can beNIR illumination sources. It should be understood that the dimillumination 104 is less bright than the flash illumination 106, andprovides sufficient ambient light for the system 100 to detect objectsin a scene as viewed by the rolling shutter camera.

The system 100 includes a rolling shutter camera 108 including a frame110 with a field-of-view. The rolling shutter camera 108 is configuredto capture one or more images (e.g., still frame images, video images,combinations thereof, or the like). The rolling shutter camera 108 isconfigured to initially capture an image of the scene and the object inthe scene under dim illumination 104 conditions. The system 100 includesan adaptive trigger module 112 configured to be executed by a processingdevice 114 having a processor 116 (e.g., a controller). Althoughillustrated as separate components from the rolling shutter camera 108,it should be understood that in some embodiments, the rolling shuttercamera 108 can include the illumination sources 102, the adaptivetrigger module 112, the processing device 114, or the like. In someembodiments, the processing device 114 can be part of a centralcomputing system 118. When executed, the adaptive trigger module 112 cananalyze the captured image of the scene illuminated by the dimillumination 104 and detects the region of interest 120 within thescene. For example, the adaptive trigger module 112 can detect andidentify the region of interest 120 as one of more eyes of the user, andstores the rows of the frame 110 corresponding to the region of interest120 in a database 122 (e.g., a local or remote database).

Based on the rows of the frame 110 corresponding to the region ofinterest 120, the adaptive trigger module 112 arranges a flash pulsedelay 124 between the start of image writing by the rolling shuttercamera 108 and a trigger of the flash illumination 106 such that theflash illumination 108 coincides with the identified region of interest120. For example, if the eyes of the user are the region of interest 120corresponding with rows 400-600 of the frame 110, the adaptive triggermodule 112 arranges the flash pulse delay 124 such that the flashillumination 106 is triggered to illuminate the object during rows400-600. Thus, rather than triggering the flash illumination 106 at thesame time as the start of image writing by the rolling shutter camera108, the image writing can start before triggering of the flashillumination 106 and the flash illumination 106 is only triggered toilluminate the region of interest 120. Such flash delay 124 ensures thatthe region of interest 120 is illuminated in the images 126 captured bythe rolling shutter camera 108. The resulting image 126 generallyincludes a stripe of flash illumination 106 extending across the image126 and over the eyes of the user (see, e.g., FIG. 9). Depending on thelength of the exposure time, the height of the stripe of flashillumination 106 can be greater or smaller relative to the top andbottom of the image 126.

In some embodiments, the adaptive trigger module 112 can include a facefinder algorithm that locates the face and/or features of the face inthe scene. The face finder algorithm can therefore locate the faceidentifies one or more eyes of the face as the region of interest 120.Although discussed herein as eyes of a user, it should be understoodthat the region of interest 120 can be a unique identifier associatedwith a physical item that can be detected by an identifier finderalgorithm of the adaptive trigger module 112. For example, theidentifier finder algorithm of the adaptive trigger module 112 can beused to detect, e.g., a barcode, a QR code, or the like, on a physicalitem, identifies such unique identifier as the region of interest 120,and adjusts the flash delay 124 to ensure that the unique identifier isilluminated during capture of the image 126.

The adaptive trigger module 112 can be configured to track movement ofthe object within the field-of-view or frame 110 of the rolling shuttercamera 108. In some embodiments, the adaptive trigger module 112 can beconfigured to continuously scan the scene in the frame 110 to detect theposition of the region of interest 120. If the user moves such that theregion of interest 120 in the frame 110 is not centered or changesrelative to the previously detected rows for the region of interest 120,the adaptive trigger module 112 can determine the new rows correspondingto the region of interest 120, stores the new rows in the database 122,and adjusts the flash delay 124 to coincide with the new rows for theregion of interest 120. Thus, an object moving in the frame 110 of therolling shutter camera 108 can be tracked by the adaptive trigger module112 to allow for the region of interest 120 of a moving object to beproperly illuminated by the flash illumination 106.

The system 100 includes a feedback module 128 configured to be executedby the processing device 114 and/or the central computing system 118. Insome embodiments, the rolling shutter camera 108 can include thefeedback module 128. When executed, the feedback module 128 receives asinput the images 126 captured by the rolling shutter camera 108 andanalyzes the region of interest 120 captured in the image 126 todetermine if the region of interest 120 is illuminated by the stripe offlash illumination 106. If the region of interest 120 is illuminated bythe stripe of flash illumination 106, the feedback module 128electronically outputs such findings to the adaptive trigger module 112and no changes are made in the flash delay 124. If the region ofinterest 120 is not illuminated (or only partially illuminated) by thestripe of flash illumination 106, the feedback module 128 electronicallyoutputs such findings to the adaptive trigger module 112. Based on thefeedback from the feedback module 128, the adaptive trigger module 112analyzes the frame 110 to locate the region of interest 120, determinesthe new rows associated with the region of interest 120, and adjusts theflash pulse delay 124 to trigger the flash illumination 106 at theappropriate rows coinciding with the region of interest 120. Thefeedback loop can be continuously performed to ensure the region ofinterest 120 is always illuminated by the stripe of flash illumination106.

The system 100 can include a user interface 130 with a graphical userinterface (GUI) 132 for receiving input from a user and for outputtinginformation to the user. For example, the user interface 130 can be usedto initiate the process performed by the system 100. As a furtherexample, the user interface 130 can output an audio and/or visual alarmto the user when the region of interest 120 is no longer centered in theframe 110. The system 100 can include a communication interface 134configured to provide a means for electronic transmission betweencomponents of the system 100, e.g., the illumination sources 102, theprocessing device 114, the rolling shutter camera 108, the adaptivetrigger module 112, the database 122, the user interface 130, thecentral computing system 118, and feedback module 128, or the like.

FIG. 10 is a diagrammatic view of an exemplary biometric analysis system200 (hereinafter “system 200”) of the present disclosure. The system 200includes an illumination source 202 that provides dim illumination tothe subject 204 in the scene. In some embodiments, the illuminationsource 202 can provide 1 ms NIR pulses to the scene. In someembodiments, the illumination source 202 can be an NIR light source notconnected to the camera 208. The illumination source 202 can bepositioned a distance 206 from the subject 204. In some embodiments, theillumination source 202 can also be configured to provide the flashillumination to the subject 204.

The system 200 includes a camera 208 including a rolling shutter (e.g.,a rolling shutter camera, such as a smartphone camera, or the like)configured to capture one or more images of the subject. The camera 208can have a field-of-view represented by area 216, including the regionof interest of the subject 204. In some embodiments, the camera 208includes an illumination source 210 (e.g., an integrated NIR lightsource) configured to provide flash illumination to a region of interest(e.g., the eyes of the subject 204). As an example, area 212 indicatesthe coverage of the NIR flash illumination provided by the illuminationsource 210, with the region of interest on the subject 204 being withinthe area 212. The camera 208 can be spaced by a distance 214 from thesubject 204. In FIG. 10, the illumination source 202 appears separatefrom camera 202, however, one skilled in the art shall appreciate that,in some embodiments, the illumination source 202 can be incorporatedinto the camera 208 assembly such that the camera 208 assembly iscapable of providing both the dim illumination and flash illumination tothe subject 204.

FIG. 11 is a diagrammatic view of a frame action 300 of a rollingshutter camera of the exemplary biometric analysis systems disclosedherein. The frame action 300 includes a total frame time 302. Ambientlight 304 having a low illumination level 306 can be provided for all orpart of the total frame time 302 by a dim illumination source and/orsunlight. The total camera exposure time 308 indicates when the rollingshutter camera begins and ends image writing and read-out.

Based on the determination of the region of interest and thecorresponding rows of the frame, a pulse of flash illumination 310(e.g., NIR from a light-emitting diode (LED) illumination source) istriggered to coincide with the rows of the region of interest. The pulseof flash illumination 310 has a time or pulse width 312 that issignificantly smaller than the camera exposure time 308, and anillumination level 314 that is brighter or higher than the level 306 ofthe ambient light 304. The region of interest is thereby illuminated bythe flash illumination 310 while the remaining rows of the capturedimage are only illuminated by the ambient light 304.

In some embodiments, a 1280×960 sensor can be used with the rollingshutter camera. In some embodiments, a 120 fps VGA (640×480) sensor canbe used with the rolling shutter camera to allow for full frame exposurein 4 ms, and can be synchronized with an approximately 4 ms LED flashevery 8^(th) frame. The VGA output can provide (unscaled) 15 fpsfeedback to the user facing the monitor of the system. The 4 ms canprovide sufficient flash pulse while allowing for cost effective use ofan LED and rolling shutter accommodation, and allowing for eye safety.

In some embodiments, a bright light (e.g., approximately 850 nm LED, twoLEDs) can be used for the flash pulse. The systems can therefore havehigh pulsed current capabilities. The rolling shutter camera can have ahigh quality camera lens and NIR filtering. In some embodiments, the NIRfilter can be tighter than 100 nm around the LED center wavelength. Insome embodiments, the system can include optics with a modulationtransfer function (MTF) optimized for the spatial frequencies that enterthe system. In some embodiments, the system can include preprocessing ofiris images for a particular spectrum of spatial frequencies (e.g., low,medium, high, or the like).

FIG. 12 is a flowchart illustrating an exemplary process 400 ofimplementing the biometric analysis systems disclosed herein. To begin,at step 402, a scene and an object in the scene are illuminated with dimillumination from one or more illumination sources. At step 404, thescene is analyzed with an adaptive trigger module to detect the object(or a region of interest associated with the object) in the scene duringdim illumination. At step 406, a position in a frame of a rollingshutter camera is determined with the adaptive trigger module, theposition coinciding with the detected object (or region of interestassociated with the object) in the scene.

At step 408, a delay is arranged by the adaptive trigger module betweena start of image writing by the rolling shutter camera and a trigger ofthe illumination sources such that a stripe of flash illuminationprovided by the illumination sources coincides with the detected object(or region of interest associated with the object) in the scene. At step410, movement of the object is tracked within a field-of-view of therolling shutter camera with the adaptive trigger module. At step 412,the delay between the start of image writing by the rolling shuttercamera and the trigger of the illumination sources is modified with theadaptive trigger module based on detected movement of the object (orregion of interest associated with the object) out of the field-of-view.

FIG. 13 is a flowchart illustrating an exemplary process 500 ofimplementing the biometric analysis systems disclosed herein. To begin,at step 502, the adaptive trigger module can set the flash delay at 0ms, the flash duration equal to the time of the full frame, and theflash brightness to low. At step 504, a full frame image can be acquiredwith the rolling shutter camera under dim illumination. At step 506, theadaptive trigger module analyzes the image captured at step 504 andlocates the region of interest in the image.

At step 508, the adaptive trigger module sets the flash delay to a valuegreater than 0 ms, the flash duration to short (e.g., a pulse), and theflash brightness to high (e.g., higher than the dim illumination) toilluminate the region of interest. At step 510, the adaptive triggermodule measures the position of the object of interest within the regionof interest (e.g., eyes of the user located on the user's face). At step512, if the object of interest is within the region of interest, theprocess 500 continues a loop to constantly (or at predeterminedfrequencies of time) ensure that the object is maintained within theregion of interest. At step 514, if the object of interest is near anedge of the frame or region of interest, the process 500 performs step516 to correct the flash delay such that the object is centered withinthe region of interest. The region of interest can thereby be maintainedin the flash illumination stripe despite relative motion of the objectand/or the camera. In some embodiments, the process can include a loopthat analyzes the captures images to control the intensity of the flashillumination, thereby avoiding saturation of the object.

FIG. 14 is a block diagram of a computing device 600 in accordance withexemplary embodiments of the present disclosure. The computing device600 includes one or more non-transitory computer-readable media forstoring one or more computer-executable instructions or software forimplementing exemplary embodiments. The non-transitory computer-readablemedia may include, but are not limited to, one or more types of hardwarememory, non-transitory tangible media (for example, one or more magneticstorage disks, one or more optical disks, one or more flash drives), andthe like. For example, memory 606 included in the computing device 600may store computer-readable and computer-executable instructions orsoftware for implementing exemplary embodiments of the presentdisclosure (e.g., instructions for operating the illumination sources,instructions for operating the processing device, instructions foroperating the rolling shutter camera, instructions for operating theadaptive trigger module, instructions for operating the communicationinterface, instructions for operating the user interface, instructionsfor operating the central computing system, instructions for operatingthe feedback module, combinations thereof, or the like). The computingdevice 600 also includes configurable and/or programmable processor 602and associated core 604, and optionally, one or more additionalconfigurable and/or programmable processor(s) 602′ and associatedcore(s) 604′ (for example, in the case of computer systems havingmultiple processors/cores), for executing computer-readable andcomputer-executable instructions or software stored in the memory 606and other programs for controlling system hardware. Processor 602 andprocessor(s) 602′ may each be a single core processor or multiple core(604 and 604′) processor.

Virtualization may be employed in the computing device 600 so thatinfrastructure and resources in the computing device 600 may be shareddynamically. A virtual machine 614 may be provided to handle a processrunning on multiple processors so that the process appears to be usingonly one computing resource rather than multiple computing resources.Multiple virtual machines may also be used with one processor. Memory606 may include a computer system memory or random access memory, suchas DRAM, SRAM, EDO RAM, and the like. Memory 606 may include other typesof memory as well, or combinations thereof.

A user may interact with the computing device 600 through a visualdisplay device 618 (e.g., a personal computer, a mobile smart device, orthe like), such as a computer monitor, which may display one or moreuser interfaces 620 (e.g., a graphical user interface) that may beprovided in accordance with exemplary embodiments. The computing device600 may include other I/O devices for receiving input from a user, forexample, a camera, a sensor, a keyboard or any suitable multi-pointtouch interface 608, a pointing device 610 (e.g., a mouse). The keyboard608 and the pointing device 610 may be coupled to the visual displaydevice 618. The computing device 600 may include other suitableconventional I/O peripherals.

The computing device 600 may also include one or more storage devices624, such as a hard-drive, CD-ROM, eMMC (MultiMediaCard), SD (securedigital) card, flash drive, non-volatile storage media, or othercomputer readable media, for storing data and computer-readableinstructions and/or software that implement exemplary embodiments of thebiometric analysis systems described herein. Exemplary storage device624 may also store one or more databases 626 for storing any suitableinformation required to implement exemplary embodiments. For example,exemplary storage device 624 can store one or more databases 626 forstoring information, such as data relating to captured images 126 underdim illumination 104 and flash illumination 106, regions of interest120, flash delay 124, combinations thereof, or the like, andcomputer-readable instructions and/or software that implement exemplaryembodiments described herein. The databases 626 may be updated bymanually or automatically at any suitable time to add, delete, and/orupdate one or more items in the databases.

The computing device 600 can include a network interface 612 configuredto interface via one or more network devices 622 with one or morenetworks, for example, Local Area Network (LAN), Wide Area Network (WAN)or the Internet through a variety of connections including, but notlimited to, standard telephone lines, LAN or WAN links (for example,802.11, T1, T3, 56 kb, X.25), broadband connections (for example, ISDN,Frame Relay, ATM), wireless connections, controller area network (CAN),or some combination of any or all of the above. The network interface612 may include a built-in network adapter, network interface card,PCMCIA network card, PCI/PCIe network adapter, SD adapter, Bluetoothadapter, card bus network adapter, wireless network adapter, USB networkadapter, modem or any other device suitable for interfacing thecomputing device 600 to any type of network capable of communication andperforming the operations described herein. Moreover, the computingdevice 600 may be any computer system, such as a workstation, desktopcomputer, server, laptop, handheld computer, tablet computer (e.g., thetablet computer), mobile computing or communication device (e.g., thesmart phone communication device), an embedded computing platform, orother form of computing or telecommunications device that is capable ofcommunication and that has sufficient processor power and memorycapacity to perform the operations described herein.

The computing device 600 may run any operating system 616, such as anyof the versions of the Microsoft® Windows® operating systems, thedifferent releases of the Unix and Linux operating systems, any versionof the MacOS® for Macintosh computers, any embedded operating system,any real-time operating system, any open source operating system, anyproprietary operating system, or any other operating system capable ofrunning on the computing device and performing the operations describedherein. In exemplary embodiments, the operating system 616 may be run innative mode or emulated mode. In an exemplary embodiment, the operatingsystem 616 may be run on one or more cloud machine instances.

FIG. 15 is a block diagram of an exemplary biometric analysis systemenvironment 700 in accordance with exemplary embodiments of the presentdisclosure. The environment 700 can include servers 702, 704 configuredto be in communication with one or more illumination sources 706, one ormore rolling shutter cameras 708, one or more adaptive trigger modules710, a feedback module 712, a user interface 714, and a centralcomputing system 716 via a communication platform 922, which can be anynetwork over which information can be transmitted between devicescommunicatively coupled to the network. For example, the communicationplatform 722 can be the Internet, Intranet, virtual private network(VPN), wide area network (WAN), local area network (LAN), and the like.In some embodiments, the communication platform 722 can be part of acloud environment.

The environment 700 can include repositories or databases 718, 720,which can be in communication with the servers 702, 904, as well as theone or more illumination sources 706, one or more rolling shuttercameras 708, one or more adaptive trigger modules 710, the feedbackmodule 712, the user interface 714, and the central computing system716, via the communications platform 722.

In exemplary embodiments, the servers 702, 704, one or more illuminationsources 706, one or more rolling shutter cameras 708, one or moreadaptive trigger modules 710, the feedback module 712, the userinterface 714, and the central computing system 716 can be implementedas computing devices (e.g., computing device 600). Those skilled in theart will recognize that the databases 718, 720 can be incorporated intoone or more of the servers 702, 704. In some embodiments, the database718 can store data relating to captured images, regions of interest 120,flash delay 124, combinations thereof, or the like, can be distributedover multiple databases 718, 720.

While exemplary embodiments have been described herein, it is expresslynoted that these embodiments should not be construed as limiting, butrather that additions and modifications to what is expressly describedherein also are included within the scope of the invention. Moreover, itis to be understood that the features of the various embodimentsdescribed herein are not mutually exclusive and can exist in variouscombinations and permutations, even if such combinations or permutationsare not made express herein, without departing from the spirit and scopeof the invention.

1. A biometric analysis system, comprising: one or more illuminationsources configured to provide dim illumination to a scene including anobject and configured to provide flash illumination to the object in thescene; a rolling shutter camera configured to capture one or moreimages; and an adaptive trigger module configured to (i) analyze thescene to detect the object in the scene during dim illumination of thescene, (ii) determine a position in a frame of the rolling shuttercamera that coincides with the detected object in the scene, and (iii)arrange a delay between a start of image writing by the rolling shuttercamera and a trigger of the one or more illumination sources such that astripe of the flash illumination coincides with the detected object inthe scene.
 2. The biometric analysis system of claim 1, wherein theadaptive trigger module is configured to track movement of the objectwithin a field-of-view of the rolling shutter camera.
 3. The biometricanalysis system of claim 2, wherein the adaptive trigger module isconfigured to modify the delay between the start of image writing by therolling shutter camera and the trigger of the one or more illuminationsources based on detected movement of the object within thefield-of-view.
 4. The biometric analysis system of claim 1, wherein theadaptive trigger module is configured to detect a region of interest ofthe object and arranges the delay such that the stripe of flashillumination coincides with the detected region of interest of theobject.
 5. The biometric analysis system of claim 4, wherein the regionof interest of the object includes eyes of a person.
 6. The biometricanalysis system of claim 1, wherein the object is a person, and whereinthe adaptive trigger module comprises a face finder configured to detecta face of the person.
 7. The biometric analysis system of claim 1,wherein the object is a physical item, and the adaptive trigger modulecomprises an identifier finder configured to detect a unique identifierassociated with the physical item.
 8. The biometric analysis system ofclaim 7, wherein the unique identifier is a barcode or a quick response(QR) code.
 9. The biometric analysis system of claim 1, wherein the oneor more illumination sources are configured to provide the flashillumination as a synchronized pulse of flash illumination.
 10. Thebiometric analysis system of claim 1, wherein the flash illuminationprovided by the one or more illumination sources is brighter than thedim illumination provided by the one or more illumination sources. 11.The biometric analysis system of claim 1, wherein the one or moreillumination sources comprise a first illumination source configured toprovide the dim illumination and a second illumination source configuredto provide the flash illumination.
 12. The biometric analysis system ofclaim 1, wherein the one or more illumination sources are near infraredillumination sources.
 13. The biometric analysis system of claim 1,wherein the one or more illumination sources are ambient light.
 14. Thebiometric analysis system of claim 1, wherein the adaptive triggermodule is configured to sweep an illuminated stripe down the frame asthe rolling shutter camera captures the one or more images, analyzes anilluminated section of the one or more images to identify a region ofinterest in the illuminated section, and stops sweeping of theilluminated stripe when the region of interest is identified.
 15. Thebiometric analysis system of claim 1 provided as a smartphone havingsaid one or more illumination sources, said rolling shutter camera, andsaid adaptive trigger module.
 16. A biometric analysis system,comprising: one or more illumination sources configured to provide dimillumination to a scene including a subject and configured to provideflash illumination to the subject in the scene; a rolling shutter cameraconfigured to capture one or more images; and an adaptive trigger moduleconfigured to (i) analyze the scene to detect eyes of the subject in thescene during dim illumination of the scene, (ii) identify the eyes ofthe subject as a region of interest, (iii) determine a position in aframe of the rolling shutter camera that coincides with the identifiedregion of interest, and (iv) arrange a flash pulse delay between a startof image writing by the rolling shutter camera and a trigger of the oneor more illumination sources such that a stripe of the flashillumination coincides with the identified region of interest.
 17. Thebiometric analysis system of claim 16, wherein the flash pulse delayensures that the illuminated region of interest is maintained in acenter of the frame of the rolling shutter camera.
 18. The biometricanalysis system of claim 16, comprising a feedback module configured toanalyze a captured image of the region of interest and determine if theregion of interest is illuminated by the stripe of the flashillumination.
 19. The biometric analysis system of claim 18, wherein theadaptive trigger module is configured to adjust the flash pulse delaybased on the determination of the feedback module to ensure that theregion of interest is illuminated by the stripe of the flashillumination.
 20. The biometric analysis system of claim 16 provided asa smartphone having said one or more illumination sources, said rollingshutter camera, and said adaptive trigger module. 21-24. (canceled)